Whenever you have cleared that opening, continue to follow the Animal Crossing Items way a westerly way until you go over a huge stone.
Eat a piece of organic product from your stock and afterward break the stone by whacking it with your digging tool, which will uncover an iron chunk to gather.
A touch of backtracking now. Simply head to where the three Animal Crossing Items for Sale bits of wood were from prior and there will be another stone needing crushing.
